Waterlogged. The science of hydration.

01 Nov Waterlogged. The science of hydration.

Bottled fluid is a huge industry estimated to be worth USD$52 billion. The purpose of this industry is profit with their claim being that that hydration is a good thing. Most of us carry a bottle of fluid thinking it is good for us. Athletes- serious and amateur, “push fluids” thinking that it will help performance. Parents and teachers urge our children to drink. The water bottle and coloured fluids are everywhere. Science tells a different story. Pushing fluids can put you in hospital and kill you. At best, it will slow you down[1]. To drink, or not to drink? That is the question.

The Dehydration Story

Between 1920 and 1960 running race times improved rapidly. Athletes who drank fluids were considered weak. In the 1960’s mining research suggested that dehydration and heatstroke could be prevented by drinking water with salt and sugar. In 1960’s Dr Robert Cade developed Gatorade – water, glucose and salt. A football team that trialled it won the college division. With some corporate marketing, Gatorade took off, triggering a multi-billion dollar industry.

When running exploded in the 1980’s sports drinks became serious business. They sponsored sports authorities and academics. Quaker Oats, who owned Gatorade in the 80’s sponsored exotic conferences for sports doctors. Then they “gifted” the American College of Sports Medicine (ACSM) and were the sole sponsor for the Australian Institute of Sport. Predictably, ACSM and other medical groups produced hydration guidelines that helped the sports drink industry boom and profit.

The rate of running time improvements declined over this period.

As many accumulated money and fame, sports scientists in South Africa and New Zealand began to collect disturbing evidence. Very simply put, they could not find evidence for dehydration or heatstroke in endurance sport. Further, they discovered that athletes with the greatest fluid loss were often winning. Those that were pushing fluids as recommended and maintaining weight were collapsing, going to hospital and, in a dozen tragic cases, dying.

They were not dying from dehydration or heat stroke. They were dying from fluid overload. When we drink too much we dilute our body sodium (exercise-associated hyponatraemia or EAH). Fluid enters cells causing swelling. The brain is sensitive to being waterlogged. Brain function declines, breathing can stop and the swollen brain blocks arterial blood flow causing death.

Profit Trumps Science and Safety

So, imagine this. From the mid 1980’s to mid 2000’s the profits of sports drinks followed the same exponential upwards curve as EAH, hospitalisation and death from over-hydration. The science of Professor Noakes and Dr Speedy was sound and well known by the late 1980’s. They were not invited to the exotic conferences. Gatorade-sponsored medical journal review boards rejected their papers. The evidence was clear that profit damaged and killed athletes however medical authorities continued to advocate damaging hydration practices.

Gatorade was massively involved in the US military. Hydration became a “weapon” and soldiers started to collapse and die. By the 1990’s the military recognised this and reversed hydration guidelines. Sports drinks shifted their marketing attention to the general public.

Eventually, in 2005, brave journals published the facts around hydration which by this time were irrefutable. After 20 years of ignoring the science, the ACSM modified its guidelines to drink to thirst.

The sports drink industry paid little attention. They continue to boom and promote hydration. Most athletes, parents and young people continue to push fluids. In NZ and South Africa where caution was advised to athletes, EAH declined to virtually nil and medical support for long distance events became practically redundant.

The Basics of Fluid Physiology

Humans evolved on the hot, dry plains of Africa. Water was often scarce. Hunting and gathering took our ancestors out for 30 km walks and runs in 38-degree heat most days of the week. We are well adapted to heat stress and dehydration. We sweat to cool, and if water is low our body rapidly releases ADH to protect fluid supplies. Salt and electrolyte loss is too minimal to require replacement.

Heat stroke only happens in very extreme environments and during short, high intensity races. It is quickly reversed by cooling. Dehydration leads to irresistible thirst, long before the body is compromised. As noted above, athletes with the most dehydration by body weight are usually amongst the winners.

The body will slow down and seek fluid long before dehydration causes serious injury. While on combat duties in southern Africa, we seldom needed more than a litre of water per day. Yet we covered 40km a day for several days in a row with heavy packs and weapons in 38-degrees. No-one collapsed or needed medical help.

Despite ubiquitous guidelines to drink 8 glasses of water per day, scientists admit freely that they can find no evidence for benefits. If we do drink too much, we quickly lose thirst and excrete the excess fluid – a waste of valuable time as an athlete or executive. For most of us, drinking from bottles is pointless. The sugars in some bottled drinks are a major factor in weight gain and diabetes and the plastics cause endocrine disruption. Plastic bottles are a major threat to our planet.

What causes Collapse, Hospitalisation and Death?

The most common cause of collapse in sport is a drop in blood pressure at the end of a race. The legs stop pounding and blood pools in the muscles depriving the brain of blood. The solution is to lie down and lift the legs. Recovery is immediate. Doctors, drips, electrolytes and ambulances are unnecessary.

In short, extreme races heat stroke is possible. Rectal temperature quickly identifies the problem and these athletes need to jump in an ice-bath. Recovery is immediate.

In some people, the signals to stop drinking and excrete water when overhydrated fail. If we recommend pushing fluids to them, they become waterlogged (EAH). They fail to perform in the race, some become fatigued and many collapse during or after the race. In some cases the brain swells blocking the brain cavity and death follows. EAH is difficult to treat. Prevention is the only sensible practice – don’t push fluids!

How we should drink?

Trust your body

If you are thirsty, drink water in small amounts

If you want to win, train with limited fluid replacement

Never push fluids beyond thirst – this is true for yourself, your children and athletes

The dangers of Bisphenol A and phthalates in plastic bottles and the catastrophic environmental impact of sports and sugary drinks is a story for another day.

[1] Challenging Beliefs, Tim Noakes, 2013. The ideas expressed are drawn from Professor Noakes research and commentary expressed in this book. I strongly encourage skeptics and athletes to read this book.